The present invention relates to a novel gas-blast circuit-breakers having a conductor structure suitable for heat gas flow treatment.
In general, gas-blast circuit-breakers include an arc-extinctive chamber disposed in an insulating gas, an operating mechanism for operating a mover disposed within the arc-extinctive chamber, and an operating device using a hydraulic pressure or the like; the arc-extinctive chamber has a fixed contact, a movable contact, an insulating nozzle, a puffer cylinder, a piston, and a shield for buffering an electric field. These are disclosed for example in Japanese Patent Laid-open Nos. 8-195147, and 8-195149.
Conventional gas-blast circuit-breakers include an arc-extinctive chamber, a fixed contact, a movable contact, an insulating nozzle, a puffer cylinder, an insulating rod, a piston, and an operating device that drives the insulating rod. The movable contact disposed in the arc-extinctive chamber is coupled to the operating device by way of the insulating rod, a pin and a lever so as to open/close the circuit-breaker. In the circuit-breaker having such a structure, a fixed conductor having the fixed contact secured thereto is formed of a straight hollow conductor having a plurality of openings. With this configuration, in a case of interrupting a large current such as a rated interrupting current, an insulating gas that is sprayed to an arc generated between poles is heated with this arc to be brought to high temperatures. Since the high temperature heat gas deteriorates dielectric strength, heat gas treatment is one of critical factors in exploiting sufficient performance of the circuit-breaker.
To suppress the effect of ground and pole-to-pole insulation reductions due to the above stated heat gas, the conventional circuit-breakers have employed a method of enlarging a tank diameter so as to extend a ground insulation distance, or a method of increasing an operating speed of an insulating unit by raise an operating force so as to extend the pole-to-pole insulation distance at the time of interruption; however, this poses a problem regarding the size reduction of circuit-breakers.
It is an object of the present invention to provide a gas-blasted circuit-breaker provided with a shield that is most suitable in terms of an operation of adjusting a flow of heat gas, a cooling effect of the heat gas, and insulating performance for a fixed conductor to which the heat gas is sprayed.
According to an aspect of the present invention, there is provided a gas-blasted circuit-breaker including a movable arc contact; a fixed arc contact opposed to the movable arc contact; an insulating nozzle disposed at the movable arc contact on the fixed arc contact side thereof; a puffer cylinder disposed on the side opposite to the insulating nozzle; a hollow conductor that holds the fixed arc contact opposed to the insulating nozzle; an insulating rod connected to the puffer cylinder; and a fixed piston fitted inside the puffer cylinder; wherein an insulating gas is ejected to a space between the puffer cylinder and the fixed piston by driving the insulating rod and is sprayed to an arc generated upon interruption of a current; and wherein the hollow conductor is in a cylindrical shape having a cross section parallel to the axis thereof, the cross section being smaller in diameter on the downstream side of a flow of insulating gas, the hollow conductor having a closed end on the downstream side of the flow of insulating gas, and the hollow conductor has a cylindrical barrel portion provided with a plurality of openings.
Preferably, the cylindrical barrel portion has three stages of an upstream part, an intermediate part, and a downstream part with respect to the flow of insulating gas in a cross-section parallel to the axis thereof, and the intermediate part is made progressively smaller toward the downstream side thereof and is provided with the openings.
According to another aspect of the present invention, there is provided a gas-blasted circuit-breaker including a movable arc contact; a fixed arc contact opposed to the movable arc contact; an insulating nozzle disposed at the movable arc contact on the fixed arc contact side thereof; a puffer cylinder disposed on the side opposite to the insulating nozzle; a conductor secured to the fixed arc contact opposed to the insulating nozzle; an insulating rod connected to the puffer cylinder; and a fixed piston fitted inside the puffer cylinder; wherein an insulating gas is ejected to a space between the puffer cylinder and the fixed piston by driving the insulating rod and is sprayed to an arc generated upon interruption of a current; and wherein the conductor includes a semicylindrical member having an opening on the downstream side of a flow of insulating gas and a cross-section being parallel to the axis of the conductor and being smaller on the downstream side of the flow of insulating gas, and a semicylindrical shield member that is joined to both side portions of the opening side of the semicylindrical member on the side portions of a cylindrical portion in the longitudinal direction on the upstream side of the flow of insulating gas, and the semicylindrical shield member has a shape in which the distal end thereof on the downstream side of the flow of insulating gas is closed.
Preferably, a barrel portion of the semicylindrical member has three stages of an upstream part, an intermediate part and a downstream part, with respect to the flow of insulating gas, in cross-section parallel to the axis thereof, and the intermediate part is smaller in cross-section on the downstream side thereof and is provided with the opening.
Preferably, the semicylindrical shield is joined to the semicylindrical member at the distal end thereof on the downstream side of the flow of insulating gas; the semicylindrical shield member is provided over a portion extending from the fixed side the of semicylindrical member to the intermediate part thereof; and the semicylindrical member has a semispherical distal end on the downstream side of the flow of insulating gas.
According to the present invention, ground and pole-to-pole insulation performance can be assured by efficiently treating the heat gas that contributes to large current interrupting performance, and a breaker tank can be reduced in size and insulation performance can be improved.